INTRODUCTION: Recognizing the predictors of mortality among HIV-infected children will allow for concerted management that can reduce HIV-mortality in Nigeria. METHODOLOGY: A retrospective cohort study in children aged 0-15 years, between October 2010 and December 2013, at the Federal Medical Centre, Makurdi, Nigeria. Kaplan-Meier method analysed the cumulative probability of early mortality (EM) occurring at or before 6 months and after 6 months of follow-up (late mortality-LM) on a 12-month antiretroviral therapy (ART). Multivariate Cox proportional regression models were used to test for hazard ratios (HR). RESULTS: 368 children were included in the analysis contributing 81 children per 100 child-years to the 12-month ART follow-up. A significant reduction in EM rates was noted at 17.3 deaths per 100 child-years (30 deaths) to LM rates of 3.0 deaths per 100 child-years (10 deaths), p < 0.01. At multivariate analysis, children with a high pretreatment viral load (≥10,000 copies/ml) were found to be at risk of EM (aHR; 18. 089, 95% CI; 2.428-134.77, p=0.005). Having severe immunosuppression at/or before 6 months of ART was the predictor of LM (aHR; 17.28, 95% CI; 3.844-77.700, p ≤ 0.001). CONCLUSIONS: Although a lower mortality rate is seen at 12 months of ART in our setting, predictors of HIV mortality are having high pretreatment HIV viral load and severe immunosuppression. While primary prevention of HIV infection is paramount, early identification of these predictors among our HIV-infected children for an early ART initiation can reduce further the mortality in our setting. In addition, measures to ensure a good standard of care and retention in care for a sustained virologic suppression cannot be ignored and are hereby underscored.